This invention relates to a contact thermometer, and more particularly to such a thermometer which may be adhesively applied to the patient's body and which readily indicates the patient's temperature.
Known temperature sensors utilize layers of encapsulated liquid crystals which change colors in response to changes in temperature within a predetermined temperature range to indicate the skin temperature of the patient. Typically, these known temperatures sensors utilize a flexible backing of plastic film or the like with a pressure sensitive adhesive applied thereto so that the sensor may be readily adhered to and conform to the patient's skin.
Sectors or other areas of the backing have different formulations of encapsulated liquid crystals applied thereto which indicate the patient's temperature over a specified range. However, upon flexing of the plastic film backing, the layers of the encapsulated liquid crystals often come loose from the backing or they may be otherwise damaged by the flexing. Furthermore, the limp plastic film backing offers poor heat conduction and thus if the temperature sensor is applied to various parts of the body having different surface temperatures (e.g., if part of the sensor is applied to the skin over an artery), the indicated temperature may vary considerably across the temperature sensor.
Reference may be made to such U.S. Pat. Nos. 3,561,269 and 3,661,142 for disclosure of digital thermometers in the same general field as this invention.